Effective Altruists are in some ways a comparable group to hardcore White Nationalists because they're extremely online and not that numerous.
Main difference is the culture supports EAs as the bleeding edge of current year regime thinking while it relentlessly attacks us.
Yet EAs have the same problem getting people to do anything other than comment online that we do.
I'm not sure what the exact conversion rate of sympathizers to activists is, but it's probably well under 1%.